Measuring device

ABSTRACT

A friction wheel measuring apparatus for measuring distances traveled along a machine surface, said apparatus including a counting wheel with a circular groove containing a continuous number of balls each of which actuates a counting mechanism during rotation of the counting wheel, said counting wheel being driven by tapered motion transfer rollers which are axially adjustable with respect to each other to change the diameter ratio therebetween for compensation of measuring errors due to gathering effect and wear of the internal parts over a period of time.

United States Patent Pajevic MEASURING DEVICE Primary Examiner-Harry N.Haroian [76] Inventor: Paul Prdevic; 475 N. Northwest AtmmeymarenceOBrien and Harvey Hwy., Park Ridge, ll]. 60068 Jacobson [22] Filed:Sept. 15, 1971 [21] Appl. No.: 180,561 [57] ABSTRACT A friction wheelmeasuring apparatus for measuring distances traveled along a machinesurface, said appalll rams including a counting wheel with a circulargroove [58] Fleid M 141 R containing a continuous number of balls eachof which r 235/95 91 actuates a counting mechanism during rotation ofthe counting wheel, said counting wheel being driven by tapered motiontransfer rollers which are axially adjust- [56] References Cited ablewith respect to each other to change the diameter UNITED STATES PATENTSratio therebetween for compensation of measuring er- 2,74l,03l 4/l956Martin et al. 33/ 141 R or due to gathering effect and wear of theinternal 2,878,566 Mellen parts over a period of time 3,3l 1,985 4/l967Hodge 33/141 R 24 Claims, 7 Drawing Figures I I i 56 a4, 4 68 r '1. W 72I I1 4 a Q 48 52 i H I I 3 5 66 4 20 I8 MEASURING DEVICE The presentinvention is generally related to measuring devices and, moreparticularly, to friction wheel devices for measuring the distance oftravel along a surface associated with a piece of machinery or the like.The invention is intended primarily for use on machine tools where, inresponse to relative travel between first and second guiding members ofthe machine tool, the apparatus provides a measurement of the relativetravel between a cutting member and the work being machined, such as onengine lathes, milling machines, shaving machines, drill presses, andthe like.

Nearly all machines of this type include a pair of guiding members, oneof which moves relative to the other to produce travel between thecutting member and the workpiece. For example, such a pair of guidingmembers may take the form of a carriage and a bed associated with anengine lathe. Another such pair of guide members are the carriage andcross feed associated therewith on a typical engine lathe. These guidemembers are provided with one or more flat machine surfaces which may beused as a measuring surface over which a metering wheel associated withthe present invention travels.

In the past, various friction wheel measuring devices have been providedto furnish machinists with readings indicative of the movement betweenthe abovementioned guide members associated with machine tools. A commonproblem with such measuring devices is that they are not provided withan adequate means of calibration to compensate for the wear of internalparts and errors attributable to gathering" effect. Wear of internalparts may result in slippage or backlash which adversely affects theaccuracy of the readings. The gathering" effect introduces error due todeformation of the surface material upon which pressure is exerted by amotion sensing or metering wheel. The amount of error due to gatheringis dependent upon the properties of the guide surface and the meteringwheel materials. Thus, friction wheel measuring devices may not beproperly calibrated at the factory, but must be adjusted uponinstallation. While several devices have been proposed with means ofcompensation for gathering effect error, such have not includedcompensation for the wear of internal parts over a period of time.

It is an object of the present invention to provide a novel frictionwheel measuring apparatus including means for compensation of error dueto both gathering effect and the wear of internal parts which may occurover a period of time.

Another object of the present invention is to provide a versatilefriction wheel measuring device which includes tapered motion transferrollers and wheels which may be axially adjusted relative to each otherto change the effective diameter ratio therebetween, therebycompensating forgathering effect error and errors attributable to thewear of internal parts.

It is a further object of the present invention to provide a uniquefriction wheel measuring device which includes a relatively largecounting wheel having a circular groove formed therein carrying aplurality of abutting counting balls adapted to actuate a countingmechanism for digital readout of the measurements of travel between theassociated guide members.

Still another object of the present invention is to provide a versatilefriction wheel measuring device which is extremely accurate, compact,durable, and long lasting, yet, relatively inexpensive to manufacture.

These together with other objects and advantages which will becomesubsequently apparent reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawings forming a part hereof, whereinlike numerals refer to like parts throughout, and in which:

FIG. 1 is an elevational view of the measuring apparatus of the presentinvention mounted to a guide member of a typical piece of machinery.

FIG. 2 is a sectional view taken along section 22 of FIG. 1.

FIG. 3 is a sectional view taken along section 3-3 of FIG. 2.

FIG. 4 is a partial sectional view of the wiper assembly associated withthe present invention.

FIG. 5 is a partial plan view of the wiper assembly shown in FIG. 4.

FIG. 6 is a partial elevational view of the counting wheel associatedwith the present invention.

FIG. 7 is a partial sectional view of a readout dial associated with amodified form of the present invention.

Referring now, more particularly, to FIGS. 1 and 2, the measuringapparatus of the present invention is generally indicated by the numeral10 and includes a pair of oppositely disposed flange members 12 and 14which are adapted to fit over a rail or guide member 16 associated witha typical piece of tooling machinery. In an actual installation, themeasuring device 10 is affixed or connected to a second guide memberassociated with the same piece of machinery, such that relative movementbetween the guide members is measured by the apparatus, the readout ofsuch measure ment being visible through a display window 18 on the faceof the apparatus housing 20.

Movement between the measuring apparatus and guide member 16 is sensedby a pair of metering rollers 22 and 24 which are adapted to engageguide member 16 for imparting rotation to a third metering roller 26affixed to a motion sensing shaft 28. A pair of wiper arms 30 and 32 arepivotally mounted to the motion sensing shaft 28, as best illustrated inFIGS. 4 and 5. These anns are provided with relatively sharp end edgeportions 34 and 36 which are adapted to clean the guide member duringtravel thereon. In addition, the wiper arms may be provided with a pairof felt pads 36 and 38 which also help to clean the surfaces of guidemember 16 to assure positive engagement with the motion transfer rollers22 and 24. A coil spring 42 extends around shaft 28 with its oppositeends engaging top surfaces of wiper arms 30 and 32 to bias themtowardthe guide member together with meter rollers 22 and 24 rotatably mountedto the wiper arms by way of shafts 23 and 25.

It will be appreciated that by providing a pair of meter rollers, ratherthan a single meter roller as with conventional measuring devices, amore positive transfer of motion to the secondary rollers is assured, inboth directions of travel. In addition, the preferred embodiment of thepresent invention is provided with a pressure wheel or roller 44engaging an opposite surface of guide member 16 under the influence of apair of coil springs 46 of the compression type. Preferably, pressureroller 44 is mounted at its opposite ends to a pair of bearings 48 and50 received by a pair of generally oblong slots 52 and 54 formed in theapparatus housing. Pressure of the coil springs 46 may be adjusted by apair of setscrews 56, threadedly received by the housing. Thus, byadjusting setscrews 56, the most desirable pressures of the guide membersurfaces against metering rollers 22 and 24 may be achieved. Thisarrangement, together with the above-described wiper arm assemblyassures against slippage of the meter rollers during travel of themeasuring apparatus relative to the guide member.

Rotation of the meter rollers is transferred to a tapered wheel 56 whichis keyed or otherwise affixed to shaft 28. The tapered circumferentialsurfaces of wheel 56 are adapted to engage a pair of correspondinglytapered rollers 58 and 60, which, in turn, transmit motion to a thirdtapered roller 62 joumaled to a support shaft 64 carried by bushings 66and 68 mounted in housing 20. One end of shaft 64 is attached to acounting wheel 70 for rotation thereof to actuate a counting mechanism72. In the preferred embodiment, the counting mechanism is provided withan actuation finger 74 which is sequentially engaged by a plurality ofball members 76 fixedly received in a circular groove formed in countingwheel 70. Thus, as the measuring apparatus is moved relative to guidemember 16, counting wheel 70 is rotated a predetermined amount toactuate the counting mechanism, which, in turn, displays a numbercorresponding to the distance of travel. Preferably, each counting ballcorresponds to a movement of one thousandth of an inch between themeasuring apparatus and the associated guide member. The passageof eachcounting ball provides a corresponding actuation of the countingmechanism to display a new number in the readout window.

Referring to FIG. 7, a second embodiment of the readout mechanismassociated with the present invention may be seen. lt'will beappreciated that instead of using digital counting mechanism 72 toindicate the distance traveled, a conventional dial-type indicator maybe utilized. In this form of the invention, support shaft 64 extendsbeyond housing 20 and is adapted to rotate indicating needle 78 mountedon one end of the shaft to cooperate with a face plate dial 80 withmeasurement indicia imprinted thereon. A lens or crystal 82 may besnap-fitted or otherwise fastened to the housing to provide a viewingwindow such as with conventional measuring devices. Of course, in thisform of the invention, the remainder of the measuring apparatus isidentical to that described above, with the exception of counting wheel70 which is not required.

As earlier mentioned, a common problem with conventional friction wheelmeasuring devices was that of calibration to compensate for gatheringeffect and errors due to the wear of internal parts over a period oftime. Such a dual-purpose compensation or calibration is provided by wayof the tapered surfaces associated with vwheel 56 and rollers 58, 60 and62. It will be appreciated that by changing the axial position betweentapered roller 56 and rollers 58 and 60, the effective ratio between thediameters of these members may be varied. It should be noted that motionsensing shaft 28 is mounted in housing 20 in a manner to permit axialadjustment relative thereto. The axial position of shaft 28 isdetermined by coil compression spring 84 which presses against a bearing86 near one end of the shaft,

the opposite end of the shaft being provided with a second bearing 88held in position by way of a pair of adjustable setscrews 90. Thus, bychanging the positions of setscrews 90, the axial position of taperedwheel 56 is adjusted with respect to the corresponding tapered rollers58 and to change the ratio of the diameters and thus, the travelmeasurement. It will be appreciated that since the tapered motiontransfer surfaces are at the measurement end of the motion transfertrain, adjustment thereof is effective to compensate for both wear ofthe rotating parts as well as errors attributable to gathering effects.By moving shaft 28 in the downward direction, as shown in FIG. 2, thediameter ratio is decreased, requiring additional movement between guidemember 16 and the measuring apparatus to achieve the same reading beforesuch an adjustment was made. Contrastingly, movement of shaft 28 in theupward direction increases the diameter ratio, thereby requiring lessmovement between guide member 16 and the measuring apparatus to providethe same reading obtained prior to the adjustment.

Referring to FIG. 3, the coaction between the tapered wheel and rollersmay be more fully appreciated. Tapered rollers 58 and 60 are mounted toa pair of lever arm members 92 and 94 each pivotally mounted near itscenter to support shaft 64. A coil tension spring 96 is fastened toopposite ends of lever arm members 92 and 94 in a manner which tends tobias rollers 58 and 60 toward each other and toward the tapered surfacesof wheel 56. In addition, it should be noted that the spacing betweeneach tapered roller 58 and 56 and tapered roller 62 is preset to assurepositive engagement between their corresponding tapered surfaces. Sincethe axis of rotation of the lever anns 92 and 94 is the same as that oftapered roller 62, rollers 58 and 60 remain in positive engagement withroller 62 regardless of the position they assume under the influence ofcoil spring 96. Thus, it will be appreciated that coil spring 96 assurespositive engagement between the tapered rollers and tapered wheelregardless of roller wear or change in axial position for the purposesof calibration, as explained above.

It will be appreciated that the rollers and wheels associated with thepresent invention may be made from relatively rigid materials includingsteel, plastics or hard rubber. Of course, minor changes in materials orthe number or exact location of the rollers or wheels is deemed to fallwithin the scope of the present invention. The measuring device of thepresent invention is capable of responding to the slightest movementbetween the apparatus and guide surface and eliminates errors due towear, backlash, and gathering effect, and, is accurate to ten thousandthof an inch. Since accurate repeatability is assured, costly errors arereduced, resulting in a substantial savings in set-up time and laborcosts.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly all suitable modifications and equivalentsmay be resorted to, falling within the scope of the invention.

What is claimed as new is as follows:

1. A device for measuring movement along a surface, said devicecomprising: a housing, a motion sensing roller rotatably mounted by saidhousing and adapted to engage the surface, a counting wheel operativelyconnected to said motion sensing roller, a continuous plurality ofcounting members mounted in a circular pattern around said countingwheel, and means adjacent said counting wheel for counting the number ofmembers moved therepast and displaying a corresponding numberrepresentative of the distance moved over the surface, said countingmembers comprising a plurality of groove-mounted balls abutting eachother around said circular pattern formed in said counting wheel.

2. The structure set forth in claim 1 wherein said counting meansincludes a movable sensing finger operatively engaging said circle ofcounting balls for movement thereby.

3. The structure set forth in claim 1 wherein said device includes amotion transfer wheel operatively connected to said motion sensingroller and having tapered circumferential side surfaces, and at leastone oppositely tapered motion transfer roller engaging the taperedsurfaces of said motion transfer wheel and being operatively connectedto said counting wheel.

4. The structure set forth in claim 3 wherein said device includes meansfor adjustment of the axial position of said motion transfer wheelrelative to said motion transfer roller to adjust the diameter ratiotherebetween.

5. The structure set forth in claim 4 wherein said adjustment meansincludes screw means mounted in said housing for axial displacement ofsaid motion transfer wheel relative to said motion transfer roller.

6. The structure set forth in claim 4 wherein said device includes meansbiasing said motion transfer roller and said motion transfer wheeltogether to assure positive frictional engagement therebetween.

7. The structure set forth in claim 6 wherein said device includes firstand second motion transfer rollers engaging said motion transfer wheel,said motion transfer rollers being supported by a pair of pivotallymounted lever arms.

8. The structure set forth in claim 7 wherein said lever arms each hasfirst and second ends and are pivotally mounted intermediate the firstand second ends, said motion transfer rollers being mounted to saidfirst ends, said biasing means including a tension spring mountedbetween the second ends of said lever arms to bias said motion transferrollers toward each other and against said motion transfer wheel.

9. The structure set forth in claim 8 wherein said device includes athird motion transfer roller engaging said first and second motiontransfer rollers and rotatably mounted about the pivot axis of saidlever arms.

10. The structure set forth in claim 4 wherein said device includesfirst and second motion sensing rollers adapted to engage the surfacefor rotation during movement of the device relative to the surface, anda third motion sensing roller rotatably mounted by said housing andengaging said first and second motion sensing rollers, said third motionsensing roller and said motion transfer wheel being affixed to a commonshaft for the transfer of rotation therebetween.

11. The structure set forth in claim 10 wherein said device includes apair of cleaning arms pivotally mounted to said shaft and carrying saidfirst and second motion sensing rollers.

12. The structure set forth in claim 11 wherein said device includesmeans biasing said motion sensing rollers and said cleaning arms towardthe surface for the cleaning thereof during movement and to assurepositive engagement between the motion sensing rollers and the surface.

113. A device for measuring movement along a surface, said devicecomprising: a housing, a motion sensing roller rotatably supported bysaid housing and adapted to engage the surface, first and second motiontransfer members rotatable about first and second axes, respectively,and having oppositely tapered surfaces operatively engaging each otherfor the transfer of rotation therebetween, said first motion transfermember being operatively connected to said motion sensing roller,measurement indicating means operatively connected to said secondtapered motion transfer member for providing measurement readingscorresponding to the distance traveled over the surface, and means foradjusting the relative axial positions of said first and second taperedmotion transfer members to change the effective diameter ratiotherebetween to calibrate the device.

14. The structure set forth in claim 13 wherein one of said motiontransfer members is affixed to a rotatable shaft supported by saidhousing, and said adjustment means includes means connected to saidhousing for selective axial displacement of said shaft.

15. The structure set forth in claim 14 wherein one end of said shaft isoperatively engaged by a compression spring biasing the shaft in theaxial direction and the opposite end of said shaft is operativelyengaged by said adjustment means connected to said housing.

16. The structure set forth in claim 15 wherein said device includesmeans for biasing said first and second motion transfer members towardeach other to insure positive frictional engagement therebetween.

17. The structure set forth in claim 16 wherein said device includes athird tapered motion transfer member engaging said first tapered motiontransfer member, said second and third motion transfer members beingrotatably supported by a pair of pivotally mounted lever arms.

18. The structure set forth in claim 17 wherein said lever arms eachinclude first and second ends and are pivotally mounted intermediate thefirst and second ends, said second and third motion transfer membersbeing rotatably mounted to said first lever ends, said biasing meansincluding a tension spring mounted between the second ends of said leverarms to bias said second and third motion transfer members toward eachother and against first motion transfer member.

19. The structure set forth in claim 18 wherein said device includes afourth tapered motion transfer member engaging said second and thirdmotion transfer members and rotatably mounted about the pivot axis ofsaid lever arms.

20. A device for measuring movement, said device comprising: a housing,a motion sensing roller 'rotatably supported by said housing for sensingthe movement to be measured, first and second motion transfer membersrotatably supported by said housing and frictionally engaging each otherfor rotation about their respective axes, said first motion transfermember being operatively connected to said motion sensing roller,measurement indicating means operatively connected to said second motiontransfer member for providing measurement readings corresponding to themovement, at least one of said motion transfer members including anaxially tapered surface frictionally engaging the other motion transfermember to transfer rotation therebetween, and means for adjusting therelative axial positions of said first and second motion transfermembers to selectively change the effective turn ratio therebetween.

21. The structure set forth in claim 20 wherein said device includesmeans for biasing said first and second motion transfer members towardeach other to insure positive frictional engagement therebetween.

22. The structure set forth in claim 21 wherein said device includes athird motion transfer member engag ing said first motion transfermember, said third motion transfer member and said second motiontransfer member being rotatably supported by a pair of pivotally mountedlever arms.

23. The structure set forth in claim 22 wherein said lever arms eachinclude first and second ends and are pivotally mounted intermediatesaid first and second ends, said third motion transfer member and saidsecond motion transfer member geing rotatably mounted to said firstlever ends, said biasing means including a tension spring mountedbetween said second lever ends to bias said third motion transfer memberand said second motion transfer member toward said first motion transfermember.

24. The structure set forth in claim 23 wherein said device includes afourth motion transfer member engaging said second and third motiontransfer members and rotatably mounted about the pivot axis of saidlever arms.

1. A device for measuring movement along a surface, said devicecomprising: a housing, a motion sensing roller rotatably mounted by saidhousing and adapted to engage the surface, a counting wheel operativelyconnected to said motion sensing roller, a continuous plurality ofcounting members mounted in a circular pattern around said countingwheel, and means adjacent said counting wheel for counting the number ofmembers moved therepast and displaying a corresponding numberrepresentative of the distance moved over the surface, said countingmembers comprising a plurality of groove-mounted balls abutting eachother around said circular pattern formed in said counting wheel.
 2. Thestructure set forth in claim 1 wherein said counting means includes amovable sensing finger operatively engaging said circle of countingballs for movement thereby.
 3. The structure set forth in claim 1wherein said device includes a motion transfer wheel operativelyconnected to said motion sensing roller and having taperedcircumferential side surfaces, and at least one oppositely taperedmotion transfer roller engaging the tapered surfaces of said motiontransfer wheel and being operatively connected to said counting wheel.4. The structure set forth in claim 3 wherein said device includes meansfor adjustment of the axial position of said motion transfer wheelrelative to said motion transfer roller to adjust the diameter ratiotherebetween.
 5. The structure set forth in claim 4 wherein saidadjustment means includes screw means mounted in said housing for axialdisplacement of said motion transfer wheel relative to said motiontransfer roller.
 6. The structure set forth in claim 4 wherein saiddevice includes means biasing said motion transfer roller and saidmotion transfer wheel together to assure positive frictional engagementtherebetween.
 7. The structure set forth in claim 6 wherein said deviceincludes first and second motion transfer rollers engaging said motiontransfer wheel, said motion transfer rollers being supported by a pairof pivotally mounted lever arms.
 8. The structure set forth in claim 7wherein said lever arms each has first and second ends and are pivotallymounted intermediate the first and second ends, said motion transferrollers being mounted to said first ends, said biasing means including atension spring mounted between the second ends of said lever arms tobias said motion transfer rollers toward each other and against saidmotion transfer wheel.
 9. The structure set forth in claim 8 whereinsaid device includes a third motion transfer roller engaging said firstand second motion transfer rollers and rotatably mounted about the pivotaxis of said lever arms.
 10. The structure set forth in claim 4 whereinsaid device includes first and second motion sensing rollers adapted toengage the surface for rotation during movement of the device relativeto the surface, and a third motion sensing roller rotatably mounted bysaid housing and engaging said first and second motion sensing rollers,said third motion sensing roller and said motion transfer wheel beingaffixed to a common shaft for the transfer of rotation therebetween. 11.The structure set forth in claim 10 wherein said device includes a pairof cleaning arms pivotally mounted to said shaft and carrying said firstand second motion sensing rollers.
 12. The structure set forth in claim11 wherein said device includes means biasing said motion sensingrollers and said cleaning arms toward the surface for the cleaningthereof during movement and to assure positive engagement between themotion sensing rollers and the surface.
 13. A device for measuringmovement along a surface, said device comprising: a housing, a motionsensing roller rotatably supported by said housing and adapted to engagethe surface, first and second motion transfer members rotatable aboutfirst and second axes, respectively, and having oppositely taperedsurfaces operatively engaging each other for the transfer of rotationtherebetween, said first motion transfer member being operativelyconnected to said motion sensing roller, measurement indicating meansoperatively connected to said second tapered motion transfer member forproviding measurement readings corresponding to the distance traveledover the surface, and means for adjusting the relative axial positionsof said first and second tapered motion transfer members to change theeffective diameter ratio therebetween to calibrate the device.
 14. Thestructure set forth in claim 13 wherein one of said motion transfermembers is affixed to a rotatable shaft supported by said housing, andsaid adjustment means includes means connected to said housing forselective axial displacement of said shaft.
 15. The structure set forthin claim 14 wherein one end of said shaft is operatively engaged by acompression spring biasing the shaft in the axial direction and theopposite end of said shaft is operatively engaged by said adjustmentmeans connected to said housing.
 16. The structure set forth in claim 15wherein said device includes means for biasing said first and secondmotion transfer members toward each other to insure positive frictionalengagement therebetween.
 17. The structure set forth in claim 16 whereinsaid device includes a third tapered motion transfer member engagingsaid first tapered motion transfer member, said second anD third motiontransfer members being rotatably supported by a pair of pivotallymounted lever arms.
 18. The structure set forth in claim 17 wherein saidlever arms each include first and second ends and are pivotally mountedintermediate the first and second ends, said second and third motiontransfer members being rotatably mounted to said first lever ends, saidbiasing means including a tension spring mounted between the second endsof said lever arms to bias said second and third motion transfer memberstoward each other and against first motion transfer member.
 19. Thestructure set forth in claim 18 wherein said device includes a fourthtapered motion transfer member engaging said second and third motiontransfer members and rotatably mounted about the pivot axis of saidlever arms.
 20. A device for measuring movement, said device comprising:a housing, a motion sensing roller rotatably supported by said housingfor sensing the movement to be measured, first and second motiontransfer members rotatably supported by said housing and frictionallyengaging each other for rotation about their respective axes, said firstmotion transfer member being operatively connected to said motionsensing roller, measurement indicating means operatively connected tosaid second motion transfer member for providing measurement readingscorresponding to the movement, at least one of said motion transfermembers including an axially tapered surface frictionally engaging theother motion transfer member to transfer rotation therebetween, andmeans for adjusting the relative axial positions of said first andsecond motion transfer members to selectively change the effective turnratio therebetween.
 21. The structure set forth in claim 20 wherein saiddevice includes means for biasing said first and second motion transfermembers toward each other to insure positive frictional engagementtherebetween.
 22. The structure set forth in claim 21 wherein saiddevice includes a third motion transfer member engaging said firstmotion transfer member, said third motion transfer member and saidsecond motion transfer member being rotatably supported by a pair ofpivotally mounted lever arms.
 23. The structure set forth in claim 22wherein said lever arms each include first and second ends and arepivotally mounted intermediate said first and second ends, said thirdmotion transfer member and said second motion transfer member geingrotatably mounted to said first lever ends, said biasing means includinga tension spring mounted between said second lever ends to bias saidthird motion transfer member and said second motion transfer membertoward said first motion transfer member.
 24. The structure set forth inclaim 23 wherein said device includes a fourth motion transfer memberengaging said second and third motion transfer members and rotatablymounted about the pivot axis of said lever arms.